One-time-use cameras with film pre-loaded by the camera manufacturer and typically including a flash illumination feature are very popular with consumers. It is important for the continued commercial success of these cameras that they provide good quality, reliable operation at the lowest possible product cost. One-time-use cameras are currently available that utilize Advance Photo System (APS) film and that have provision for providing a selection of desired print aspect ratios. APS specifications include provision for optically recording (or not recording) data bits (exposed blips) in the film margin adjacent each image frame that signal the photofinisher which print aspect ratio to apply. These blips are colloquially referred to as "fat bits". In the specification, there are three available print aspect ratios, H, P and C, which roughly correspond to HDTV, panoramic and conventional 35 mm aspect ratios, respectively. No recorded fat bit specifies the H aspect ratio, a single recorded fat bit specifies the P aspect ratio and two recorded fat bits specify the C aspect ratio.
In commonly assigned, co-pending U.S. application Ser. No. 09/149,688, there is shown a flash circuit for a one-time-use camera in combination with a data bit recording circuit for recording fat bits on the film. The data recording circuit employs a light emitting diode (LED) which is powered from the main flash capacitor of the flash circuit. The flash circuit is designed to maintain a minimum voltage on the flash capacitor substantially equal to the battery supply voltage to insure that there is sufficient voltage to illuminate the LED even if the flash capacitor is fully self-discharged following a long period of non-use of the camera. While effective for its purpose, this arrangement requires that the data recording circuit include a relatively costly high-voltage-rated transistor and a zener diode for protecting the LED from the high voltage of the flash capacitor when fully charged and for limiting the LED current to the relatively low level of 5 to 10 milliamps needed for illumination of the LED.
In copending, commonly assigned U.S. Application Serial Number [Atty. Docket 78752], there is disclosed a data bit recording circuit for use with a "one touch" flash charger circuit that utilizes battery voltage, either directly from the battery or, alternatively, from a battery-charged auxiliary storage capacitor, to power the LED rather than the main flash charge capacitor. This arrangement permits elimination of the high-voltage-rated transistor and zener diode from the recording circuit and thereby lessens the cost of the circuit. However, it does require the use of an additional capacitor to provide the backup power source for the LED and the arrangement does cause some small amount of power drain on the battery to maintain the capacitor at the no-load battery voltage level. Additionally, the circuit disclosed in aforementioned copending application Serial Number [Atty. Docket 78752] is designed for use with a "one touch" flash circuit which starts the flash charging circuit upon momentary closure of a charge start switch, the charge circuit continuing to charge until feedback from the flash capacitor indicates full charge is reached. An additional feedback from the flash illumination circuit automatically restarts the charge circuit each time a picture is taken. While definitely a convenience to the camera user, the illustrated "one touch" circuit is relatively costly. As a result, it may be desirable for product cost reasons to utilize a conventional manually operated charging circuit which charges only so long as a charger start switch is held closed by the camera user. However, if a data recording circuit powered directly by a battery source having a sufficient output voltage to effect illumination of the LED data recording device is used with a manual charging circuit powered by the same battery, it is possible in some cases that a user may take a picture while still holding the charger ON/OFF switch closed. In this case, the charger load on the battery would reduce the battery output voltage and render it insufficient to effect illumination of the LED.
U.S. Pat. No. 5,784,658--Hata et al., discloses an LED data bit recording circuit operated in conjunction with a manually actuated flash charger circuit powered by a 1.5 volt battery source. Because the 1.5 volt battery is insufficient to effect illumination of the LED, data recording is accomplished by pulses generated in the primary winding of the charger circuit step-up transformer. This necessarily requires that the charger circuit be running when data recording is effected since the primary winding pulses are the only source of effective power to operate the LED recording device (or devices). The disclosed circuit arrangement, thus requires the combination of a switching transistor and a synchronizing switch to actuate the charger oscillator transistor in order to generate the primary winding pules needed to operate the LED data recording device. The switching transistor is used to bypass the manual charger ON/OFF switch and the synchronizing switch responds to initiation of a flash illumination to enable the switching transistor during the transitory time the flash trigger switch is closed. While useful for data recording purposes, it requires extra parts to ensure the required starting of the charger circuit in order to effect data recording. It is thus preferred normally to operate the data recording circuit directly from a battery source having an output voltage that is sufficient to effect illumination of the LED recording device.
Therefore, there still remains a need for a data recording circuit to optically record data on the film that further reduces the parts count, and therefore the cost of the data recording feature, and that operates reliably to record the data bits even when operating battery voltage is reduced due to load conditions on the battery, such as during operation of the camera flash charging circuit.